1. Field of the Invention
This invention relates to an x-ray generating apparatus which produces precise, short pulses of X-ray energy and can do so asynchronously. The X ray generating apparatus and associated method are also disclosed with respect to inspection of objects such as containers for products. An inspection is carried out utilizing computer image processing techniques to analyze an image produced using the X-ray pulses in order to detect foreign materials, defects and the like in the container, or to check for missing components.
2. Description of the Prior Art
A critical step in the manufacturing of any type of consumer product, especially in the area of processed foods and medicines, is the inspection of containers to determine if there are defects, foreign materials or any undesired object present in any container. Foreign materials, such as broken glass or metal chips, if contained in processed foods are a serious threat to consumer health and safety. Thus, it is desirable that essentially every container that is manufactured and/or processed in a plant be inspected before leaving the plant. However, when a large number of containers are manufactured, it can be extremely time consuming and expensive to subject each container to a rigorous inspection.
One known technique of inspecting containers for defects involves sampling. This involves statistical techniques for estimating the presence or absence of foreign materials in packages by inspecting a statistically determined number of containers. Of course, this technique is not perfect as it is limited by the sampling nature of the technique, and inevitably some containers with defects will leave the plant and may eventually reach the consumer.
Alternatively, if equipment failure which could result in contamination is discovered at a manufacturing plant, all production is stopped and items generated subsequent to the last time the equipment was checked are quarantined. The items are then either destroyed or, in some cases, they are x-rayed and individually inspected to check for contaminants. This procedure can result in production delays and lost inventory.
Although it has been known to provide X-ray inspection of containers, the inspection of fast moving objects requires X-ray pulses of very short duration. It is known to provide precisely timed ultra-short X-ray pulses for various purposes. See U.S. Pat. Nos. 2,879,404 and 3,103,591. These patents are primarily concerned with medical uses of X-ray technology, i.e., angiography, where it is desired to not only get high resolution pictures of moving blood vessels but also to limit patient dosages of X-rays.
It is also known to provide high voltage X-ray pulses in synchronization with a camera shutter, an AC cycle, or a pulse generator in the primary circuit of a transformer See U.S. Pat. Nos. 3,109,093, 3,294,973 and 4,614,999. These devices are not particularly useful when it is desired to generate pulses asynchronously in response to external events, such as the arrival of containers at an inspection point.
Despite these prior art methods and devices, there remains a need for an efficient cost effective way to inspect every container on a high speed assembly line. There also remains a need for an X-ray pulse generator that is triggered by the arrival of the container to be inspected at the inspection position.